Today, the railways are the main economic power in terms of transport and technology and occupy an important share in national and regional-local development. However, for the same railway to be economically justified and acceptable, the growth trend of freight and passenger traffic should be the most important. Attracting operators should be a fundamental task of the infrastructure manager, and this is planned, but the problem of infrastructure must ultimately be solved. As part of the modernization of railway traffic management in the ŽTPZagreb region, in cooperation with the Department of Telecommunications of Jiaotong University, the technology and operational capabilities of the SpDrL-30 system in traffic safety were studied.The purpose of this article is to describe the device itself and illustrate the use of the device. Errors read by the device will also be displayed. When troubleshooting, it is necessary to find the part that is not working properly as soon as possible. Since the equipment consists of relay groups that are completely replaced in the event of a fault, it is necessary to determine which group is defective. With a full understanding of the operation of equipment in this simple configuration, it is easy to continue to study equipment with complex configurations.